1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method for manufacturing the electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus comprising such an electrophotographic photosensitive member.
2. Description of the Related Arts
Among electrophotographic photosensitive members, so-called an organic electrophotographic photosensitive member is widespread which is an electrophotographic photosensitive member having a photosensitive layer (an organic photosensitive layer) made of an organic material for a photoconductive material (a charge-generating material or a charge-transporting material) arranged on a cylindrical support, because of having the advantages of a low price, high productivity and the like. Among the organic electrophotographic photosensitive members, an electrophotographic photosensitive member having a so-called multilayer-type photosensitive layer is in the mainstream, which is a photosensitive layer having both a charge-generating layer containing a charge-generating material, such as a photoconductive dye or a photoconductive pigment, and a charge-transporting layer containing a charge-transporting material, such as a photoconductive polymer or a photoconductive low-molecular-weight compound, layered one on another, because of having advantages of high sensitivity and high durability.
The surface of an electrophotographic photosensitive member directly receives an electrical external force and/or a mechanical external force such as electrification (primary electrification), exposure (image exposure), development with a toner, the transfer of a toner to a transfer material such as paper, the cleaning of a remaining toner after transferring, so that the electrophotographic photosensitive member is required to have durability to the external forces. Specifically, the electrophotographic photosensitive member is required to have durability to scratches and abrasion occurring on the surface due to the external forces, or equivalently, scratch resistance and abrasion resistance.
One of a technology for improving the scratch resistance and abrasion resistance of the surface of an organic electrophotographic photosensitive member is, for instance, Japanese Patent Application Laid-Open No. H02-127652 that discloses an electrophotographic photosensitive member which uses a cured layer with the use of a curable resin for a binder resin, as a surface layer (a layer located on the outermost surface of an electrophotographic photosensitive member, or equivalently, a layer farthest isolated from a support).
In addition, Japanese Patent Application Laid-Open No. H05-216249 and Japanese Patent Application Laid-Open No. H07-072640 discloses an electrophotographic photosensitive member using a charge-transporting cured layer formed by curing and polymerizing a monomer having a carbon-to-carbon double bond and a charge-transportable monomer having a carbon-to-carbon double bond with heat or light energy, as a surface layer.
Furthermore, Japanese Patent Application Laid-Open No. 2000-066424 and Japanese Patent Application Laid-Open No. 2000-066425 discloses an electrophotographic photosensitive member which uses a charge-transporting cured layer formed by curing and polymerizing a hole-transportable compound having a chain-polymerizable functional group in the same molecule with the energy of electron beams, as a surface layer.
As described above, in recent years, as a technology of improving the scratch resistance and the abrasion resistance of the surface of an organic electrophotographic photosensitive member, a technology of forming the surface layer of an electrophotographic photosensitive member with a cured layer and thereby increasing the mechanical strength of the surface layer has been established.
As described above, an electrophotographic photosensitive member is used in an electrophotographic image-forming process comprising an electrification step, an exposure step, a development step, a transferring step and a cleaning step.
Out of an electrophotographic image-forming process, the cleaning step of cleaning the surface of the electrophotographic photosensitive member by removing a toner remaining in the electrophotographic photosensitive member after the transferring step, so-called a remaining toner after transferring, is an important step for obtaining a clear image.
As a cleaning method, a method of scraping a remaining toner after transfer by abutting a cleaning blade with an electrophotographic photosensitive member so as not to make a gap between the cleaning blade and the electrophotographic photosensitive member, and preventing the passing of a toner is in a mainstream, because of having the advantages of an inexpensive cost and an easiness of designing.
Particularly, when forming images in full colors, desired colors are reproduced by superimposing a plurality of toners such as magenta, cyan, yellow and black, and a larger amount of toners is used than when forming images in monochrome, so that a cleaning method of using a cleaning blade is most suitable.
However, a cleaning method of using a cleaning blade has the disadvantages of easily causing the chattering and folding back of the cleaning blade and the chipping of an edge, because a frictional force between the cleaning blade and an electrophotographic photosensitive member is great. Here, the chattering of a cleaning blade is a phenomenon that the cleaning blade vibrates by an increased frictional resistance between the cleaning blade and the surface of an electrophotographic photosensitive member, and the folding back of the cleaning blade is a phenomenon that the cleaning blade flips toward a moving direction of the electrophotographic photosensitive member.
The problems with a cleaning blade become more remarkable as the surface layer of an electrophotographic photosensitive member has higher mechanical strength, or equivalently, the surface of the electrophotographic photosensitive member becomes more resistant to abrasion.
In addition, the surface layer of an organic electrophotographic photosensitive member is generally formed with a dip coating, but then, the surface of a surface layer formed with the dip coating, or equivalently, the surface of an electrophotographic photosensitive member becomes smoother, and a contact area between a cleaning blade and the surface of the electrophotographic photosensitive member becomes large to increase frictional resistance between the cleaning blade and the surface of the electrophotographic photosensitive member, so that the above described problems become more remarkable.
As one method of inhibiting the chattering and folding back of a cleaning blade and the chipping of an edge, a method for adequately roughening the surface of an electrophotographic photosensitive member is known.
As a technology of roughening the surface of an electrophotographic photosensitive member, for instance, Japanese Patent Application Laid-Open No. S53-092133 discloses a technology of limiting the surface roughness of the electrophotographic photosensitive member to a defined range in order to facilitate the separation of a transferring material from the surface of the electrophotographic photosensitive member. Japanese Patent Application Laid-Open No. S53-092133 discloses a method for roughening the surface of an electrophotographic photosensitive member into an orange-peeled state by controlling drying conditions in a step of forming a surface layer.
In addition, Japanese Patent Application Laid-Open No. S52-026226 discloses a technology of roughening the surface of an electrophotographic photosensitive member by making the surface layer contain particles.
In addition, Japanese Patent Application Laid-Open No. S57-094772 discloses a technology of roughening the surface of an electrophotographic photosensitive member by polishing the surface of the surface layer with the use of a metal wire brush.
In addition, Japanese Patent Application Laid-Open No. H01-099060 discloses a technology which uses particular cleaning means and toner and roughens the surface of an organic electrophotographic photosensitive member in order to solve the flipping (folding back) of a cleaning blade and the chipping of an edge, which become problems when the cleaning means and the toner are used in an electrophotographic apparatus with a particular process speed or higher.
In addition, Japanese Patent Application Laid-Open No. H02-139566 discloses a technology of roughening the surface of an electrophotographic photosensitive member by polishing the surface of the surface layer with an abrasive film.
However, the above described conventional technologies could not sufficiently solve the above described problems of the chattering and folding back of the cleaning blade.
In addition, as another technology of roughening the surface of an electrophotographic photosensitive member, Japanese Patent Application Laid-Open No. H02-150850 discloses a technology of roughening the peripheral surface of an electrophotographic photosensitive member by blasting, in order to prevent the flipping (folding back) of a cleaning blade and the fracture (chipping) of an edge.